Interventions for Dysarthria and Aphasia

DYSARTHRIA

Therapies aim to improve the patient's speech intelligibility, volume, and fluidity by means of exercises for affected structures. Patients may be trained to slow their articulation, use shorter sentences, maximize breath support, extend the jaw's motion, and purposefully place the tongue or exaggerate articulatory movements. A modest Valsalva exercise may increase adduction of the vocal folds. By increasing vocal cord adduction and respiratory support for speech, patients with extrapyramidal disorders often improve their intelligibility (Lee Silverman Voice Treatment).134 Relaxation techniques may lessen the strained vocal quality in patients with a pseudobulbar palsy. Behavioral retraining methods include pacing vocalizations by an external cue, using delayed auditory feedback by speaking into an echoic device, and use of a Speech Enhancer (Electronic Speech Enhancement, St. Louis) that amplifies the voice and clarifies dysarthric speech.

Surface electromyographic electrodes placed over the anterior cervical strap muscles can provide feedback about laryngeal elevation.

Some patients benefit from oral prosthetic devices when weakness of muscles around the velopharyngeal port impairs resonance. A palatal lift may help both spastic and flaccid dysarthric patients. So-called pressure consonants such as t, s, and p sounds may improve with a lift in place. For very soft or monotone speech, a portable amplifier can reestablish functional communication. Apraxia of oromo-tor function, which refers to the inability to carry out volitional movements with the artic-ulators, is managed by methods that overlap those used to treat dysarthia.

APHASIA

Treatment for aphasia is based on the clinical evaluation of the patient's cognitive and linguistic assets and deficits. The therapy plan is fine tuned by standardized language and neu-ropsychologic tests, knowledge of the cortical and subcortical structures damaged, and the ongoing response to specific therapies. The patient's casual interactions with the family and rehabilitation team often broaden the analysis of the patient's linguistic and nonlinguistic strengths and weaknesses for communication. The speech therapist must assist the team, as well as the patient, to understand the processes and strategies that the patient will employ to communicate. Successful treatment approaches depend on the profile of impaired and spared abilities and build upon the patient's residual problem-solving strategies and memory. The therapist manages aspects of behavioral compensation, substitutive reorganization, and psychosocial responses to disability. Language therapists usually employ an idiosyncratic combination of techniques. Approaches to children with aphasia may differ considerably from therapy for adults, not only in regard to development, but also in relation to the greater plasticity shown in studies of children.135 Aphasia therapy, in general, is efficacious after stroke,136 which is discussed further in Chapter 9.

General Strategies

Speech therapists attempt to circumvent, deblock, or help the patient compensate for defective language behaviors. For patients with impaired expression and comprehension of language, the therapist's first challenge is to quickly obtain reliable verbal or gestural "yes-no" responses. Otherwise, aphasic patients may feel isolated, even angry and frustrated, and may withdraw from those around them. Initial treatments for aphasia often deal with tasks that relate to self-care, the immediate environment, and emotionally positive experiences. As specific syndromes of impairments evolve during assessment and treatment, a variety of specific techniques can be applied. One note of caution. Some patients become upset and withdraw from therapists and family or friends whom they perceive to be talking down to them. Nothing turns them away from therapy more than seemingly irrelevant, simple, repetitive tasks. The inpatient and outpatient rehabilitation team and family help the aphasic person most when they show patience and use consistent techniques to aid expression and comprehension.

Different models of conceptualizing language lead to variations in the approaches that may be taken.137 Models include (1) modality-specific, (2) linguistic, (3) language module processing, (4) minor hemisphere mediation, (5) functional communication, and (6) hybrid therapy approaches. Each therapy task in each of these models has its rationale, drawn from small group studies of normal and impaired subjects. Without greater knowledge of the cognitive architecture of language, however, these models will have limited success for aphasia therapy.138 Future models may combine information about processing single words, sentences, and discourse with the mem ory substrates needed for these forms of visual and auditory communication and with their physiologic and anatomic substrates drawn from functional anatomic imaging with PET, fMRI, and other tools (see Chapter 3).

Within any of the conceptual models, a patient can be diagnosed with multiple language processing impairments, instead of a specific syndrome of aphasia. The aim of the neurolin-guistic assessment of aphasia is to specify types of representations or units of language, such as simple words, word formation, sentences, and discourse, that are abnormally processed during speech, auditory comprehension, reading, and writing.139,140 For each unit, the therapist ascertains how the disturbance affects linguistic forms, such as phonemes, syntactic structures, and semantic meanings. Some of these distinctions are made by a speech therapist's traditional evaluation. For example, the therapist assesses differences in the ability to express or understand words that are familiar or novel, regular or irregular, and concrete or abstract. A traditional analysis often is not as detailed as a neurolinguistic one. Perhaps greater clarification of the nature of the patient's impairments will produce additional therapeutic strategies,141, ones that sift through the real architecture of language processing.

The most common intervention takes a stimulation-facilitation approach. Therapists employ visual and verbal cueing techniques that include picture-matching and sentence-completion tasks, along with frequent repetition and positive reinforcement as the patient approaches the desired responses (Table 5-6). One major goal is to activate connections be

Table 5-6. Traditional Aphasia Therapy Tasks

Body part identification

Contextual cueing

Word discrimination

Phonemic and semantic word retrieval strategies

Word to picture matching

Priming for responses

Yes-no response reliability

Melodic stimulation

Auditory processing at the phrase, then sentence

Graphic tasks-tracing, copying, word completions

level

Calculations

Word, phrase, then sentence level reading

Pragmatic linguistic and nonlinguistic conversational

Gestural expression and pointing

skills

Oral-motor imitation

Psychosocial supports

Phoneme, then word repetition

Verbal cueing for words and sentence completion

tween related words and meanings and to prime subjects to do this faster and more spontaneously. Some preliminary studies suggest that priming techniques (see Chapters 1 and 11) may improve certain language functions. Priming, a phenomenon present even in amnestic patients, relies on cues and prompts to drive recall of information previously provided to the subject. Patients with poor comprehension of spoken words may respond to auditory priming to complete a task, even though the patients do not comprehend the studied items.143 Auditory perceptual priming may, then, depend upon access to a prese-mantic (knowledge about the world) auditory word-form system. Few well-designed studies, however, have been published of word-word and sentence-word priming paradigms in aphasic patients.144 Such semantic priming may not be preserved in some aphasic patients, since it involves a network that includes the left inferior prefrontal cortex. Of interest, when semantic priming is intact, cortical regions that had been engaged when a word was first seen are relatively deactivated when the word reappears, which is consistent with the decrease in reaction time induced by prior exposure.145 The pathway for processing has been greased.

Related techniques that expose aphasic patients to target items also improve their performance via implicit or nonconscious memory. Implicit reading strategies help a person with an acquired alexia read. A task that requires alexic patients to name a written word tends to produce a letter-by-letter reading strategy. When instructed to make a lexical decision or semantic judgement about rapidly presented words, some patients are able to switch to a whole-word reading strategy.

The intensity and specificity of practice may be most important in testing for advantages of conceptual models for therapy. Several studies have examined this issue. One well-designed clinical trial employed a picture card game in which a group of aphasic patients were prompted to request and provide a card of depicted objects in their hand. The results suggest that behaviorally relevant mass practice for at least 3 hours a day for 10 days that also constrained the use of nonverbal communication and reinforced appropriate responses within a group setting could improve comprehension and naming skills over less intensive and formalized therapy.87 Researchers continue to ex amine how each parameter of a retraining program built upon any of these models may improve outcomes, including manipulations of the frequency and duration of a specific treatment approach, the use of blocked practice or contextual interference, the type and frequency of reinforcement with knowledge of performance and results, the advantages of group versus individual therapy, and the use of a professional therapist or trained helper.

Therapies for Specific Syndromes

A handful of techniques have been designed and evaluated for specific aphasia syndromes and neurolinguistic impairments.139,147,148 The evidence for efficacy of these structured approaches to difficulties in expression and comprehension rests on small group and case studies. Table 5-5 lists the most thoroughly evaluated adjunct techniques that include a well-documented procedure for the intervention. These approaches often overlap. For example, for several approaches, the clinician controls perseverative utterances by holding up a hand and instructing the desperate patient to watch and listen, but not try to speak. Then, the patient watches the clinician's mouth pronounce a word as the clinician taps on the patient's arm to help define the start and end of the word. The clinician repeats this approach a half-dozen times before allowing the patient to attempt the word.

Melodic intonation therapy (MIT) is one of the few interventions that can be defined and applied consistently enough to make it applicable for research.149 In MIT, therapists and patients melodically intone multisyllabic words and commonly used short phrases while the therapist taps the patient's left hand to mark each syllable.150 Words are produced with an exaggerated prosody that includes high and low pitches at short and longer durations. Gradually, the continuous voicing and tapping is withdrawn. Melodic intonation therapy works best in Broca's aphasics with sparse or stereotyped nonsense speech and good auditory comprehension. Short-term, qualitative benefits have been shown for this demanding approach. Melodic intonation therapy can also lead to gains in patients with a severe apraxia of speech. A PET study showed that word repetition during MIT compared to repetition without the sounds of MIT caused a decrease in cerebral blood flow in the right hemisphere's homologue region for Wernicke's area and increased flow to the left hemisphere, especially in Broca's area and adjacent prefrontal cortex.151 Melodic intonation therapy, then, induces a systematic change in how the acoustic features of spoken and perceived speech are engaged by the brain after a left hemispheric stroke. Intensive practice in the approach may help to reactivate the left prefrontal region in relation to improved expression. As described in Chapter 3, functional imaging studies suggest that greater recovery in aphasics occurs when peri-injury language areas are activated, rather than when nondominant homologuous cortical regions are engaged.

When a single sound, word, or phrase overwhelms any other attempted output, the voluntary control of involuntary utterance (VCIU) program can help the patient gain control over perseverative intrusions.152

The agrammatism of Broca's aphasia has been treated with the Helm-elicited language program for syntax stimulation (HELPSS), which uses a series of drawings that picture common activities. The therapist provides a brief verbal description that ends with a question about the story and contains a target sentence. After the patient responds with the target words, the patient is asked to complete the story without benefit of having heard the target sentence. Each probe seeks a target response that requires an increasingly more difficult syntactic construction.

Some patients with little or only stereotyped output, even with impaired comprehension, have responded to multiple input phoneme therapy (MIPT).154 The theory behind the approach is that markedly apractic-aphasic patients who produce only stereotypies are caught in a verbal motor loop. Once an utterance is made, the loop strengthens and each attempt at volitional speech elicits the loop. Multiple input phoneme therapy is a 22-step hierarchic program that builds from an analysis of phonemes produced by the patient. The therapist controls the patient's struggle to articulate, then elicits a target phoneme to build consonant blends, multisyllabic words, and eventually sentence production.

Response elaboration training (RET) shapes and chains the responses patients give to their descriptions of familiar activities in line drawings. The technique reinforces informational content, rather than linguistic form.

Some mute or nonfluent aphasies can acquire a limited but useful repertoire of gestures, such as those drawn from American Indian sign language.156 Sign language requires left hemisphere language areas.

Attempts to improve comprehension for patients with global and Wernicke's aphasia take many forms. The sentence level auditory comprehension (SLAC) program trains patients to discriminate consonant-vowel-consonant words that are the same or differ by only one phoneme (e.g. bill, pill, fill).157 Patients then try to associate the word sounds with the written word and later try to identify the target word embedded in a sentence. Gains in some patients have generalized to improved scores on the Token Test for comprehension. The SLAC program141 calls upon the neurolin-guist's understanding of phonemic, syntactic, and lexical deviations.

For global aphasics, nonverbal communication with pantomime through a technique called visual action therapy (VAT) may decrease limb apraxia and improve auditory comprehension.158 Patients are taught to use hand gestures with real items, then gestures without the items. Programmed instruction has been combined with operant conditioning for the global aphasic patient, but the efficacy was lim-ited.159 Another technique, called promoting aphasics' communicative effectiveness (PACE), emphasizes the ideas that need to be conveyed in face-to-face interactions during real bouts of communication with nontherapists, rather than linguistic accuracy.160 This experiential technique aims to develop any modality that can be used to transmit a message, such as limited speech, limb or facial gestures, and drawing. Success with VAT and PACE suggests that the left hemisphere has a linguistic, rather than a general symbolic specialization for the components of language. The dominant hemisphere produces sign and spoken language, whereas both hemispheres are capable of producing the nonlinguistic gestures of pantomime.161 Pointing to pictured objects with the proximal right arm may improve simultaneous vocal naming after a stroke, perhaps by activating attention in the dominant hemisphere.162

Pragmatics refers to the use of language in a social context. Along with the attentional, memory, and other cognitive problems of patient's with TBI, pragmatic communication is often impaired.163 The communication abili ties in daily living (CADL) and the pragmatic protocol164 are useful assessment tools. Behavioral training techniques can improve skills in eye contact, body posture, initiating and staying on a topic, turn-taking during conversation, adapting to listener needs, and using speech to warn, assert, request, acknowledge, or comment.

Iconic Language

After extensive training, some patients benefit from learning alternative languages. These iconic language approaches include the Blisssymbol lexicon,165 which has 100 icons for concrete objects and concepts, and computerized visual iconic communication systems (C-VIC), which employ symbols to create a syntax and vocabulary. The Lingraphica System (Lingraphi-CARE America, Palo Alto, CA) includes a laptop computer with software that combines spoken and printed words with approximately 2000 lexical items categorized by nouns, verbs, and other elements and icons with concept-images, along with story boards and anima-tion.166 An uncontrolled case series of chronic aphasic patients showed that repetitive practice with a therapist and at home with the device was associated with significant improvements on several tests of language function.167 Microcomputer-based therapies have been suggested for a hierarchical approach to apha-sic neurolinguistic impairments and for specific problems, such as to improve the ability to name items presented visually.168 Therapy with a C-VIC interface also improved the ability of chronic aphasic subjects to relearn the use of past tense verbs and to comprehend passive voiced sentences, pointing to an approach to lessen agrammatism and syntactic deficits.169 A flexible, highly interactive multimodal system for the intensive practice of language tasks that are established by a therapist needs more rigorous evaluation.

Pharmacotherapy

A 1972 trial of hyperbaric oxygen represents one of the first reasonably well-designed attempts to augment aphasia therapy with an agent.170 The intervention had no benefit. Unfortunately, hyperbaric chamber treatments of patients with chronic cognitive, language, and motor impairments is still foisted upon naïve patients in private clinics, especially in Florida and California. Pharmacotherapy given with language therapy appears to hold some promise,171,172 although the proof will require larger, carefully designed trials (see Chapter 9). Initial studies using dopaminergic agents appeared hopeful, but better designed studies failed to show efficacy across patients. As in the small trials of amphetamine for motor gains, drug therapy for aphasia may need to include focused therapy while the drug is active. Input from speech therapists about specific impairments to be targeted, interventions for these impairments, and measurable outcomes are critical for the success of clinical trials and for single-subject designs during the treatment of individual patients. Functional imaging may compliment evaluations of whether or not certain drugs increase the engagement of language regions. The data for drug interventions for aphasia after a stroke is reviewed in Chapter 9. The speech therapist can also help monitor negative effects of drugs that enter the CNS.

Therapeutic strategies in the future are likely to encompass the combined analytic approaches of speech pathology, neurolinguistics, neuropsychology, neuroimaging, pharmacology, and computer sciences. This multimodal attack should lead to theory-based treatments that will define the short-term and long-term benefits of a specific intervention on a particular aspect of language. Single-case studies and clinical trials should also address the optimal intensity, duration, and learning paradigm for a treatment.

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